It is the goal of this project to characterize solution transport and the permeability of the major regions of the pulmonary epithelium. Na ion, Cl ion, K ion, HCO3 ion water flow in the trachea, large bronchi, small bronchi and alveoli will be measured in vitro in models for each region. These models include planar and cylindrical preparations of large airways from several species, epithelial barriers that are reformed from disaggregated cells of the terminal airways, the microlavaged terminal alveolar sac of the Ringer filled, perfused left lobe of the rat lung, and the bullfrog alveolar epithelium. The effects of heavy metal salts (Cd2 ion, Hg2 ion Zn2 ion and Ni2 ion) on transepithelial solution flow in alveoli and large airways will be examined along the binding of each metal to the epithelium. Competition between metals for binding and the ability of sulfhydryl agents and other chelators to reverse binding and the biological effects will help pinpoint the locus and nature of the metal interaction with the epithelium.